As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Fibre Channel or FC systems are a particular type of information handling system. Fibre Channel is an integrated set of standards for flexible high-speed serial data transfer. A particular topology is a Fibre Channel Arbitrated Loop (FC-AL) (which may also be referred to herein as a Fibre Channel Loop or FC Loop). Current Fibre Channel Loops may have multiple subsystems or enclosures (which may also be referred to as disk enclosures, or data storage modules) with up to 126 connected devices. Note, however, that many more devices may theoretically be attached to the Fibre Channel fabric.
Most fibre channel storage sub systems are so called disk enclosures, with disk drives divided across a number of chassis. These chassis are often connected to one another and then to storage processors. Because the disk drives are connected in a loop fashion, it is a requirement that each disk drive have a unique identifier. In current fibre channel storage systems, this identification is a combination of the disk drive ID within the chassis in conjunction with the so-called shelf ID of the chassis.
Current direct attached fibre channel sub systems allow for a maximum of eight shelf IDs with 16 devices per shelf ID. This results in up to 128 possible devices on a fibre channel storage loop. Of these 128 devices, two devices per shelf ID are typically claimed by SCSI protocol overhead, resulting in a maximum configuration of 112 physical drives connected to a single direct attached fibre channel sub system.
Each fibre channel enclosure, whether it is a traditional multi drive storage enclosure (such as the power vault 650F or power vault 660F sold by Dell Computer Corporation) or a modular data storage module, is assigned one of the possible eight unique shelf IDs. Since modular storage systems typically contain between three to six drives (considerably less than the maximum of 15 physical drives) the remainder of the drive IDs which could be assigned to the shelf ID will be forfeited, reducing the total number of physical drives that can be connected to the FC Arbitrated Loop. By reducing the total number of physical drives that can be connected to the FC-AL, the FC Loop is not fully utilized and may hamper the management of storage devices within the FC Loop.